1. Field of the Invention
The present invention relates generally to laser scanning systems, and more particularly to a bar code symbol reading system in which an automatic hand-supportable laser scanner can be interchangeably utilized as either a portable hand-held laser scanner in an automatic xe2x80x9chands-onxe2x80x9d mode of operation, or as a stationary laser projection scanner in an automatic xe2x80x9chands-freexe2x80x9d mode of operation.
2. Description of Related Art
Bar code symbols have become widely used in many commercial environments such as, for example, point-of-sale (POS) stations in retail stores and supermarkets, inventory and document tracking, and diverse data control applications. To meet the growing demands of this recent innovation, bar code symbol readers of various types have been developed for scanning and decoding bar code symbol patterns, and for producing symbol character data for use as input in automated data processing systems.
In general, prior art bar code symbol readers using laser scanning mechanisms can be classified into two categories. The first category includes systems having lightweight, portable hand-held laser scanners which can be supported in the hand of a user. The user positions the hand-held laser scanner at a specified distance from the object bearing the bar code symbol, manually activates the scanner to initiate reading, and then moves the scanner over other objects bearing bar code symbols to be read. Prior art bar code symbol readers illustrative of this first category are disclosed in U.S. Pat. No. 4,387,297 to Swartz; U.S. Pat. No. 4,575,625 to Knowles; U.S. Pat. No. 4,845,349 to Cherry; U.S. Pat. No. 4,825,057 to Swartz, et al.; U.S. Pat. No. 4,903,848 to Knowles; U.S. Pat. No. 5,107,100 to Shepard, et al.; U.S. Pat. No. 5,080,456 to Katz, et al.; and U.S. Pat. No. 5,047,617 to Shepard et al.
The second category of bar code symbol readers includes systems having stationary laser scanners supported on or built into an immovable structure such as a supermarket counter. These laser scanners are referred to as countertop scanners and typically utilize a moving laser beam to create a laser scan pattern. Each object bearing a bar code symbol to be read is oriented by the user and then moved through the laser scan pattern in order to read the bar code symbol. Prior art bar code symbol scanners illustrative of this second category are disclosed in U.S. Pat. No. 4,086,476 to King; U.S. Pat. No. 4,960,985 to Knowles; and U.S. Pat. No. 4,713,532 to Knowles.
While prior art hand-held and stationary laser scanners have played an important role in the development of the bar code symbol industry, these devices have, however, suffered from a number of shortcomings and drawbacks. For example, hand-held laser scanners, although portable and lightweight, are not always convenient to use in assembly-line applications where the user processes bar coded objects over an extended period of time, or where the user requires the use of both hands in order to manipulate the objects. In some applications, hand-held laser scanners are difficult to manipulate while simultaneously moving objects or performing other tasks at a point-of-sale terminal. Stationary laser scanners, on the other hand, provide a desired degree of flexibility in many applications by allowing the user to manipulate bar coded objects with both hands. However, by their nature, stationary laser scanners render scanning large, heavy objects a difficult task as such objects must be manually moved into or through the laser scan field.
Attempting to eliminate the problems associated with the use of hand-held and stationary laser scanners, U.S. Pat. No. 4,766,297 to McMillan discloses a bar code symbol scanning system which combines the advantages of hand-held and stationary fixed laser scanners into a single scanning system which can be used in either a hands-on or hands-free mode of operation.
The bar code symbol scanning system in U.S. Pat. No. 4,766,297 includes a portable hand-held laser scanning device for generating electrical signals descriptive of a scanned bar code symbol. In the hands-on mode of operation, a trigger on the hand-held laser scanning device is manually actuated each time a bar code symbol on an object is to be read. The system further includes a fixture having a head portion for receiving and supporting the hand-held laser scanning device, and a base portion above which the head portion is supported at a predetermined distance. In the hands-free mode of operation, the hand-held laser scanning device is supported by the fixture head portion above the fixture base portion in order to allow objects bearing bar code symbols to pass between the head and base portions of the fixture. In order to detect the presence of an object between the head and base portions of the fixture, the fixture also includes an object sensor operably connected to the hand-held laser scanning device. When the object sensor senses an object between the head portion and the base portion, the object sensor automatically initiates the hand-held laser scanning device supported in the fixture to read the bar code symbol on the detected object.
While the bar code symbol scanning system of U.S. Pat. No. 4,776,297 permits reading of printed bar code information using either a portable xe2x80x9chands-onxe2x80x9d or stationary xe2x80x9chands-freexe2x80x9d mode of operation, this system suffers from several significant shortcomings and drawbacks as well.
In particular, in the hands-on mode of operation, scanning bar code symbols requires manually actuating a trigger each time a bar code symbol is to be read. In the hands-free mode of operation, scanning bar code symbols requires passing the object bearing the bar code between the head and base portions of the fixture. However, in many instances where both hands are required to manipulate a bar coded object, the object is too large to be passed between the head and base portions of the fixture and thus scanning of the bar code symbol is not possible.
Thus, there is a great need in the bar code symbol reading art for a bar code symbol reading system which overcomes the above described shortcomings and drawbacks of prior art devices and techniques, while providing greater versatility in its use.
Accordingly, it is a primary object of the present invention to provide a fully automatic bar code symbol reading system having an automatic hand-supportable laser scanning device which can be used as either a portable hand-supported laser scanner in an automatic hands-on mode of operation, or as a stationary laser projection scanner in an automatic hands-free mode operation.
It is another object of the present invention to provide such an automatic bar code symbol reading system, in which one or more bar code symbols on an object can be automatically read in a consecutive manner.
A further object is to provide such an automatic bar code symbol reading device, in which the automatic hand-supportable bar code (symbol) reading device has an infrared light object detection field which spatially encompasses at least a portion of its visible laser light scan field along the operative scanning range of the device, thereby improving the laser beam pointing efficiency of the device during the automatic bar code reading process of the present invention.
Another object of the present invention is to provide such an automatic bar code reading system in which a support frame is provided for supporting the hand-supportable housing of the device in a selected mounting position, and permitting complete gripping of the handle portion of the hand-supportable housing prior to removing it from the support frame.
A further object of the present invention is to provide such an automatic bar code symbol reading system in which the hand-supportable bar code reading device has long and short-range modes of object detection within its object detection field. In one illustrative embodiment, the long and short-range modes of object detection are manually selectable by the user by manual activation of a switch on the hand-supportable housing of the device. In another illustrative embodiment, the long-range mode of object detection is automatically selected when the hand-supportable bar code reading device is placed within the support stand during the hands-free mode of operation. In this illustrative embodiment, the short-range mode of object detection is automatically selected whenever the hand-supportable bar code reading device is picked up from the support stand and used in its hands-on mode of operation.
A further object of the present invention is to provide such an automatic bar code symbol reading system, in which the hand-supportable bar code reading device has long and short-range modes of bar code presence detection within its scan field. In one illustrative embodiment, the short-range mode of bar code presence detection is manually selectable by manual activation of a switch on the hand-supportable housing of the device. In another illustrative embodiment, the short-range mode of bar code presence detection is automatically selected when the hand-supportable bar code reading device is placed within the support stand, or alternatively, upon decoding a predesignated bar code symbol preprogrammed to induce the short-range mode of bar code presence detection. In the short-range mode of bar code presence detection, the automatic bar code reading device not only detects the presence of a bar code within the scan field by analysis of collected scan data, but it further processes the collected scan data to produce digital count data representative of the measured time interval between bar and/or space transitions. Bar code symbols present within the short-range of the scan field, produce scan data having time interval characteristics failing within a prespecified timing data range. Using the results of this analysis, only bar bode symbols scanned within the short-range field are deemed xe2x80x9cdetected,xe2x80x9d and only bar code symbols detected within the short-range of the scan field activate the decoding module of the device and thus enable bar code symbol reading.
A further object of the present invention is to provide such an automatic bar code symbol reading system in which the hand-supportable bar code reading device has long and short-range modes of bar code symbol reading within its scan field. In one illustrative embodiment, the long and short-range modes of bar code symbol reading are manually selectable by the user by manual activation of a switch on the hand-supportable housing of the device. In another embodiment, the long-range mode of object detection is automatically selected when the hand-supportable bar code reading device is placed within the support stand during the hands-free mode of operation, or alternatively, upon decoding a predesignated bar code symbol preprogrammed to induce the mode of bar code symbol reading. In this illustrative embodiment, the short-range mode of object detection is automatically selected whenever the hand-supportable bar code reading device is picked up from the support stand and used in its hands-on mode of operation. In this short-range mode of bar code symbol reading, the only decoded bar code symbols residing within the short-range portion of the scan field, are deemed xe2x80x9creadxe2x80x9d.
It is another object of the present invention to provide an automatic hand-supportable bar code reading device which has both long and short-range modes of object detection and bar code symbol reading, automatically selectable by placing the hand-supportable device within its support stand and removing it therefrom. With this particular embodiment of the present invention, the automatic bar code symbol reading system can be used in various bar code symbol reading applications, such as, for example, charge coupled device (CCD) scanner emulation and bar code xe2x80x9cmenuxe2x80x9d reading in the hands-on short-range mode of operation, and counter-top projection scanning in the hands-free long-range mode of operation.
An even further object of the present invention is to provide an automatic hand-supportable bar code reading device which prevents multiple reading of the same bar code symbol due to dwelling of the laser scanning beam upon a bar code symbol for an extended period of time.
A further object of the present invention is to provide a point-of-sale station incorporating the automatic bar code symbol reading system of the present invention.
It is a further object of the present invention to provide an automatic hand-supportable bar code reading device having a control system which has a finite number of states through which the device may pass during its automatic operation, in response to diverse conditions automatically detected within the object detection and scan fields of the device.
It is yet a further object of the present invention to provide a portable, fully automatic bar code symbol reading system which is compact, simple to use and versatile.
Yet a further object of the present invention is to provide a novel method of reading bar code symbols using a automatic hand-supportable laser scanning device.
These and further objects of the present invention will become apparent hereinafter and in the claims.